And the dispute has shown no signs of ending after talks between the two sides came to a halt today.

A spokesperson for Govia Thameslink Railway said: “We came here for serious constructive talks but sadly the RMT was not prepared to discuss details of the new role.

“We tabled, at their request, high level principles on which to move forward and they have dismissed them out of hand, offering no alternative of their own.

“This is a snub to every commuter on the Southern network who now seem condemned to four more days of strikes early next month.

“All we are doing is shifting responsibility for closing a train’s doors from the conductor to the driver, so the conductor, in their new role of on-board supervisor, can focus on customer service on the train.

“No-one will be made compulsorily redundant, no-one will get a cut in salary.

“We continue to urge the RMT to review their position and not inflict another totally unnecessary strike on our passengers.”

Mick Cash, general secretary of Union Rail, Maritime and Transport (RMT), said: “Not only have Southern management today collapsed the talks process but they have also dished out forms to sign to give an undertaking that our members will not take part in any further industrial action during this dispute. RMT has issued guidance to members that they are under no obligation to sign this form and recommending that they bin it. This is a deliberate attempt to pour fuel on the flames and deflect attention from the core safety issue at the heart of this dispute.

“The form asks members to commit to working extra days, extra hours, working rest days and overtime on strike days. It then goes on to say that members won’t be guaranteed extra work. In effect, that means that they want staff to put on record that they are willing to break the strike, but that they won’t be needed and won’t be paid.

“Southern/GTR management are now stooping so low during this dispute that their actions are not only contemptible but would also be laughable if this dispute was not so serious. Their actions are undermining any attempts to seek a negotiated solution to this dispute as they have put out this form on the very day that important talks are taking place. We can only assume that they do not want to find a settlement to this dispute as they are issuing intimidating threats, provoking members at every opportunity and acting like the worst kind of playground bullies.”

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